Are you using Mach2 or Mach3? Microstepping shouldn't reduce torque at all. It should only increase your resoloution. This may make your steps per second go into a higher KHz range to still get the rapids you want. This may cause problems.

Brett

Brett,
I use Mach2, though I tried Mach3 and had the same problem.

Miscrostepping does reduce torque, because when you switch to microstepping, then in order to maintain the same speed the driver has to send more frequent pulse rate to the motor. And if you look at a torque diagram of a step motor you can see that the torque decreases with the increase in ppm value. Anyway, that's what I know.

I've just hooked up it all to my PC (the first trials were made with a laptop) and there was the same problem. It's almost two weeks now that I'm  trying to solve this issue, before mounting the motors on the mill, and there is no progress.

Any suggestions?


Daniel

And if you look at a torque diagram of a step motor you can see that the torque decreases with the increase in ppm value. Anyway, that's what I know

This is because the decrease in torque is from the higher RPM the motor is running at. This is different from micro stepping. Steppers usualy fall off pretty quick at a certain RPM, each motor is different. Microstepping does not increase the desired RPM, it simply takes a step and divides it by the given value resulting in higher resoloution. Say you have a motor, 2.8 degrees per step x 200 = 360 degrees. Now, micro stepping x 8 it would be 1600 steps per 360 degrees. Either way, with the motor running at the same RPM, it should have the same torque. I think you are confusing RPM with PPM.   

I have sent you a personal message.

Brett

Yes. but I mean that I want to maintain the same speeds. I do not want to use microstepping and work 8 times slower.

Anyway, the microstepping issue is of no help for me. It just offsets the stalling range.

Thanks,
Daniel

HI,
  for my twopenceworth micro stepping will reduce torque at all speeds.
 When I was using steppers I did some experiments.
  Basically put a bathroom weighing scale on the bed and drive the z into it at any speed ,it will
stall the motor and note the weight. then start microstepping,and you will find
that there is less power.
     Tony

Tony, I can see where it would make a slight decrease in torque. What were the values you saw? how much difference in micro steppng Vs. full step? I had a remote session with Daniel yesterday and we got his motors turning, but he still has some things to get straight. He can stall his motors with his fingers gripping the shaft. He has just sent me a pm about his power supply, it is drastically undersized.

Brett

Bret,
  It was a while ago,I cant remember the figures,but I do remember that at 1/16 steps it was delivering
50% less torque.I googled it after and found that it was the case. try it yourself. This was one of the reasons I went to servo's.For all the wasted time I had with steppers, hours of tuning and retuning and harmonics,added to that the sloooow
rapids.I would never build another stepper system.
   Tony